Hi, SharePoint 2010 workflows are being removed from SharePoint Online. See https://support.microsoft.com/en-us/office/sharepoint-2010-workflow-retirement-1ca3fff8-9985-410a-85aa-8120f626965f.
You should instead use Power Automate which has approval flows. See https://learn.microsoft.com/en-us/power-automate/modern-approvals.